Electric switching and distributing system



May 24, 1932.

G. A. BURNHAM ELECTRIC SWITCHING AND DISTRIBUTION SYSTEM Filed Dec. 51.1927 2 Sheets-Sheet 1 4 Inverfiar.

May 24. 1932.

G. A. BURNHAM Y ELECTRIC SWITCHING AND DISTRIBUTION SYSTEM 2Sheets-Sheet 2 Filed Dec. 51, 1927 Patented May 24, 1932 GEORGE A. BURNHAM, F SAUGUS,

MASSACHUSETTS, ASSIGNOR TO CONDIT ELECTRICAL MANUFACTURING CORPORATION,OF SOUTH BOSTON, MASSACHUSETTS, A CORPORA- TION OF MASSACHUSETTSELECTRIC SWITCHING AND DISTRIBUTING SYSTEM Application filed December31, 1927. Serial No. 243,902.

This invention relates to electric switching and distribution systemsand especially to such systems operated at high potentials.

The electric switches of the system are of the oil immersed type. Whenthe switches are opened under abormal current conditions they sometimesexpell heated oil gases and vapors and flame from the switch casing. Theheated gases are fairly good conductors and, when they come in contactwith a high tension conductor, establish a conducting path over which aflash over arc can pass.

y reason of the arrangement of the system it is difficult to extinguishthe arc, so that it can cause much damage and disable the system for along period of time. As a consequence considerable care is exercised inisolating the various conductors ofthe system from each other to preventthe occurence of a flash over. Usually, however the switch terminals,and especially the joint or connection between the conductors and theswitch terminals is exposed and, since they are located at the switch,are the most likely parts of the conductorsystem to be bridged by theheated gases and the flash over arc. The joints between the switchterminals and the conductorsare difficult to insulate or to shield fromthe switch or other conducting gases, for one reason because it isnecessary, at times to break the joints and remove a switch. Variousinsulating and isolating methods have been attempted. If the joint istaped, the tape can not be quickly removed if the switch should suddenlyprove defective and should immediately be replaced by a new switch. Thetape is combustible and if it is set on fire by an arc burns and gives011' hot vapors and fumes'which may cause the system to flash over atsome point; Oil has been proposed but it is difiicult to make acontainer which will hold the oil about the joints without considerabledangeriof leakage. The oil more over is combustible and may be set onfire by the flame expelled from the switch or by a flash over in theoil. A hard insulating compound is also inflammable, can not be removedreadily and is brittle and liable to crack and thus expose the conductorand provide a path for a flash overare. I

It is an object of the present invention to provide insulating means forthe connection between a pair of conductors, and especially for theswitch terminal and thereat, which will be free from the aboveenumerated disadvantages.

A further obj ect of the invention is to provide an insulating andprotective structure for the connection between the conductor andterminal of an electric switch or other translating device whichincludes a mobile body of an insulating material and a containertherefor, the material being flowable so that it can be poured into thecontainer around the connection without difliculty and yet will notescape through small openings and will shield the conducting parts ofthe joint against access by heated gases and will act to cool the hotgases as they attempt to penetrate the mobile body.

A further object of the invention is to provide sealing means for theconnection between two conductors and particularly between a conductorand the terminal of an electric switch, which means consists of acontainer adapted to surround the joint and the insulated conductors onopposite sides of the joint and a body of sand which fills the containerand surrounds the joint and the insulated portions of the conductorsadjacent the joint, the container being characterized by being removablefrom the aforesaid relation so that the connection can be exposed foraccess.

A yet further object is generally to improve the construction ofelectric distribution systems.

Fig. 1 is a side elevation partly in section of an electric switchingsystem embodying the invention, parts unnecessary to the understandingof the invention being omitted.

Fig. 2 is a perspective view of the tubular container for the sand bodyin which the bare connection between the switch terminal and theconductor is embedded.

Fig. 3 is a perspective view of one of the retaining springs for the twohalves of the tubular container of Fig. 2.

Fig. 4 is a perspective View of the inventhe conductor bushing, asshown.

tion applied to a modified arrangement of switch and conductor.

Fig. 5 is a sectional elevation through a switching system embodying theinvention wherein the switch is enclosed within a cell and the circuitconductors are extended through the wall of the cell and are shieldedagainst contact with gases and also against passage of gases along theconductors out of the cell in accordance withthis invention.

Fig. 6 is an enlarged sectional detail of one of the conductors and itsinsulating shield or bushing of Fig. 5.

In Fig. 1 the oil immersed switch 10 is provided with terminals 12 whichare exposed at the tops of the insulating bushings 14. Circuitconductors 16 are connected by suitable joints or connectors 18 with theswitch terminals and extending upwardly through insulating bushings 20into conductor-compartments 24.

I In accordance with this invention a tubular container 26 whichpreferably is composed of insulating material, as fibre, surrounds andis spaced from the exposed connector 1'8 and the switch terminal 12 andoverlies the lower end of the insulating bushingQO and'the upper end ofthe switch bushing 14 andrests upon and is supported by the switch andspecifically by the switch A mobile body 28 of solid insulating andnon-combustible material occupies the container 26 and surrounds thejoint 18 and switchv terminal 12 and occupies the container about andabove the lower end of the bushing 20 and also about and below the topof the switch bushing 14 for such. a distance that "any heated ases'expelled'by the switch or otherwise o1=med can not penetratesaid bodyand have access 'to the exposed conductor. Said body 28 is preferablycomposed of sand, as a quartz sand, which is free from harmful amountsof forei n material such assilt and conducting metallic compounds. Thesand is practically impervious to gas and also acts to cool any heatedgas that may attempt to penetrate it so that it acts to isolate theexposed conducting elements of the system The sand against access toheated gases.

' body although composed of solid particles,

is fluids'o that it can be poured into the -top of the container whenthe container is in the position shown and thus surround the exposedconnection and, insulate it. The sand, however, cannot flow throughsmall'crevices or channels and thus cannot escape from the tubularcontainer'26 at the bottom thereof through amychannels caused ,byirregularitiesofoontact between the bottom of the tube and the bushing14. V

The tube 26 is formed of two semi-circular sectionszQGaas shown .in Fig.2, which sections are held removably in complemented relation .by a pairofcircular spring olipsi30 which surround the two sections of the tubeat the top and bottom thereof and hold them together. When theconnection is to be inspected the clips can be withdrawn and the twohalves of the tube separated. The sand within the tube can fall to thefloor of the switch com artlnent and thus expose the connection. W henthe connection is to be recovered the tube can be in its pm viousrelation and can be filled with sand.

In the modification shown in Fi l, the conductor 16a is insulated andmaies contact with the switchtenninal 12a through the connector 18a. Theenclosing tube 26b in this instance rests upon the clamping ring 32which attaches the bushing 14a to the switch 10a. In this modificationwhen it is desired to expose the connection 180., the tube can be raisedabove its seat and along the conductor 16a. The sand falls out (Ff thebottom of the tube thus uncovering the cennection. When the connectionis recovered the tube is placed in its position and sand is poured inthrough 1; e top of the tube. If necessary, the sand-can be tamped in1308 although ordinarily this is not essent' Fig. 5 shows a cellenclosed switching system wherein the oil circuit breaker 1.65 isenclosed in a cell 34 provided with a door 36 through which access canbe gained to the interior of the cell. The (all .13 vented by means of aduct .38 which communicates at one end with the upper portion oi theswitdi cell and at its other end with a convenient venting s ace as "theoutside atmos here. The bare tension conductors 1165M downwardly from ann r room of the switch house and through d: floor of said room, whichfloor comprises the ceiling ref the switch cell, and into the switchcell, and connect with the switch terminals 12b through connectors 186..Any gas which may be generated within the switch cell is preventedfrnmescaping into the com partment 39 by means of tubes or shings e2,composed preferably of insulating m terial, which surround saidconductors 15b and are extended through openings in and are secured tothe floor 40 .anddepe-nd-into the switch cell and are tenm'inated theswitch terminals. The lower ends cf the tubes are closed by .means ofwalls 44 her ing openings thereinthr h which the'conductors 161) arepassed he tubes are sufficiently large in diameter to ,prevent over fromthe conductors .to the walls of the tube when the tubes are filled withair. .A body 46 of sand fillseach tube andthus prevides an eifectivebarrier against the p: of gas upwardly through the tubes firemt switchcell. As before, the connectors 181 are insulated ztram exposure to gas.by the sand filled tubes 250 which rest at their lower ends upon theswitch frame and supround the switch bushings, the cmmeetors,

and also the lower ends of the tubes 42 and thus prevent access of gasto said connectors in the manner above set forth. Said tubes can bemoved upwardly about said tubes 4-2 to permit the sand in'said tubes 260to run outand expose the connectors 18?). In Figs. 1 and 5, theconductors 16 and 16?) can be bare since the sand bodies prevent thepassage of gases to the conductors and into the upper conductorcompartments, the sand body 28 of Fig. 1 sealing the lower end of thepassage through the bushing 20, and the sand bodies in the tubes 42 ofFig. 5 preventing passage of gas along the length of the conductors. InFig. 4 theconductor 16a has an insulating covering which prevents gasfrom contacting with its conductor and the sand body prevents access ofgas to the ex posed elements of the conductor and switch terminal at thejoint therebetween.

In Figs. 5 and 6 the conductor can be covered with a suitable insulationto with stand full line potential. In the latter case, the sand-filledenclosing tube 42 can be made smaller in diameter than if the conductorsare bare since, in this case it does not have to provide for theinsulation of the conductor. The sand body thus need be only thickenough to prevent access of gases to the conductor. If a flash overoccurs within the tube, and the insulation begins to burn, the fumes ofthe burning insulation will be entrapped by the sand, and only the gasmay escape from the tube, and this gas will be cooled by its passagethrough the sand. The sand will prevent access of air to the insulationso that any flame will be immediately extinguished.

The insulating body in the tubes surrounding the conductors preferablyis a quartz sandwhich is free from harmful amounts of foreign substancesand is of sufficient fineness to resist flow of gases through the sandbody or, at least, to cool the gases before they reach the conductors orthe atmosphere, as the case may be. 'When the passage through the sandbody is long, the sand particles can 'be coarser than when the passageis short.

While I prefer a sand body for general purposes, in some specificinstances the sand may be replaced by an equivalent body that iscomposed of small discrete insulating and non-combustible solidparticles.

I claim:

1. The combination of a pair of conductors having a breakable connectionbetween them, a removable casing surrounding said connection and alsosaid conductors thereat, and a mobile body of solid insulating materialcontained in said casing and enclosing said connection and theconductors thereat and constituting means to prevent access of aconducting gas to said connection and conductors.

2. The combination of a pair of conductors having a connection betweenthem, a removable casing surrounding said connection and also saidconductors thereat, and a mobile body of solid insulating materialcontained in said casing and enclosing said connection and theconductors thereat and said casing being removable from the aforesaidrelation to expose said connection.

3. The combination of a pair of conductors having a connection betweenthem, a remov able casing surrounding said connection and also saidconductors thereat, and a body'of sand contained in said casing andenclosing said connection and the conductors thereat and constitutingmeans to prevent access of a conducting gas to said connection andconductors.

4. The combination of a pair of vertical conductors having a connectionbetween them, a vertical casing open at the ends surrounding saidconnection and also said conductors thereat, means closing the loweropen end of said casing, and a mobile body of solid insulating materialcontained in said casing at and both above and below said connection.

5. The combination of a pair of vertical conductors having a connectionbetween them, a vertical casing open at the ends surrounding saidconnection and also said conductors thereat, means closing the loweropen end of said casing, and a mobile body of solid insulating materialcontained, in said casing at and both above and below said connectionand said casing being removable from the aforesaid relation to exposesaid connection.

6. The combination of a pair of vertical high tension conductors havinga connection between them, insulating means enclosing said conductors onopposite sides of said connection, an open-ended tube surrounding saidconnection and the insulating means of both conductors, a closure forthe lower open end of said tube, and a mobile body of solid insulatingmaterial occupying the space in said tube between the ends thereof andabout said connection and both insulating means.

7. The combination of a pair of spaced bushings, a conductor extendedtherebetween and exposed in the space between said bushings, a casingsurrounding said exposed conductor and overlying the proximate ends ofsaid bushings, and a mobile body of solid insulating material occupyingthe space between said conductor and casing and also the space betweensaid bushings and said casing and constituting a gas seal for saidconductor, said casing being movable over one of said bushings to exposethe conductor extended therebetween.

8. The combination of a depending tube, an insulating bushing spacedbelow said tube, a conductor extended through said tube and bushing, amobile body of insulating material contained in said tube about saidconductor, a vertical casing surrounding said tube and bushing and theconductor therebetween,

and a mobile body of solid insulating material occupying the spacebetween said casing and tube and bushing, and also between said casingand conductor, said casing being movable 5 upwardly over said tube toexpose-said conduetor between said tube and bushing.

9. The combination of enclosing cell having a ceiling providing with anopening therethrough, anoil immersed electric switch contained in saidcell, a'high tension conductor extended downwardly through saidceiling-opening and connected with said switch, a tube located in saidceiling-opening about Said conductor and terminated at its lower endclose to said switch, and a body of discrete pieces of solid insulatingnon-combustible material contained in said tube between its ends and insurrounding relation with said conductor and providing a seal preventingescape of hot gases from said cell through said In testimony whereof, Ihave signed my name to this specification.

GEORGE A. BURNHAM.

